The new shares will have their primary listing on the London Stock Exchange and are scheduled to start trading on July 20.

Shell is currently the sixth largest firm in London's FTSE 100 index, but a market value of more than £120bn would push it into the top two - almost on a par with oil giant BP.

Shell hopes its greater size will allow it to improve its competitive edge and lead consolidation in the industry.

Almost 98% of shareholders in the Netherlands voted in favour of unification. In London, the figure was closer to 96%.

"I think the unification will be very helpful for the company and private shareholders will benefit from that," said Shell stock owner Boudewijn Rietveldt.

"It will surely be good for the image of the company."

'Pursuit of profit'

Analysts said that while the change will simplify management structure, it will do little to solve Shell's main problem - the fact that it is not replacing its reserves of oil and gas quickly enough.

"What Shell actually needs to do is concentrate more on getting its strategy right and operationally improving performance," said Neil McMahon of Sanford Berstein.

"Just changing the nuances of the share structures of such companies [will not] in effect help them with exploration and find more oil and gas."

There have been demonstrations outside the meeting in London as environmental groups protest against continued pollution by Shell.

After chief executive Jeroen van der Veer opened the shareholders' meeting on Tuesday, management board members faced questions from activists who complained about Shell's "reckless pursuit of profit".

At close shares in Shell Transport & Trading had gained 3.2% in London, while Royal Dutch Petroleum shares added 3.5%.